When pulp or paper in the form of bales is to be dissolved for the final production of paper, the wires that keep the bales together must be removed. This may be done manually or mechanically. It is especially important to make sure that no wire remains with the pulp since this could cause great damage to the equipment in the following process steps.
The mechanical removal is usually carried out as a two-step operation. At first, the wires are cut off by means of one or more cutting devices and then the cut wires are removed. The removal is normally carried out by means of winding devices, which grab one end of the wire, or the centre of the wire and then rotate such that the wires are wound onto the device.
One such device is known from the American patent document U.S. Pat. No. 4,850,087. This known device is equipped with gripping members for transferring the wires from the place of cutting to the place of winding. This, however, adds another step, which makes the operation sensitive to possible errors.
In WO 9213768, a device is described in which the cutting and the removal are combined in one single elongated arrangement having an inner element and a surrounding tubular element, both comprising an indented edge, whereby the two elements rotate in relation to each other such that the wire is cut off and caught between the two elements, after which the elements rotate together to wind the cut wire around the arrangement.
A problem with this device is that the arrangement does not always grip the wires correctly, or on the contrary, the wires get caught between the two parts such that the operation has to be interrupted to release the wires. Furthermore, the arrangement needs a fairly complicated driving mechanism in order to accomplish all the steps.
Another problem is that it risks fraying the entire side of the bale since the cutting is carried out over the whole side of the bale instead of being centred at the positions where the wire is actually located. This results in wastage, which is undesired since it requires cleaning of the working area as well as decreases the degree of capacity utilisation of the bale material.
An object of the invention is to provide an improved device for the cutting and removal of wires from bales, which is reliable and easy to implement and which solves the above mentioned problems.
The said objects are obtained by means of the device, as disclosed in the claims, for the cutting and removal of wires from bales, such as pulp bales, paper bales and the like, which device comprises at least one cutting unit having a cutting tool for cutting off a wire that is arranged around a bale, and at least one winding unit having a winding tool for the unwinding of the cut wire from the bale.
The cutting tool of the cutting unit comprises an outer cutter and an inner cutter, which are coaxially arranged and rotatable with respect to each other, whereby the cutters comprise a cutting edge each, which are arranged to be moved towards each other when the cutters are rotated towards each other in a certain direction, in order to cut off objects, preferably bale wires, between them.
The winding unit is used to unwind and thus remove the cut wire from the bale. Said unwinding and removal are achieved by winding the wire onto the winding tool of the winding unit.
Preferably, a turning tool or turning plate is arranged at the centre of a working location W, in which the bale is intended to be positioned when its wires are cut off and removed from it, whereby the cutting unit and the winding unit are positioned opposite each other, on one side each of the working location (W), and whereby the turning tool or turning plate is arranged to be able to turn the bale 90° to relocate it into a position in which wires placed crosswise with respect to the first wires may be cut off and unwound.
Preferably, there are also driving units arranged to move the cutting unit and the winding unit towards and from the centre of the working location, between a working position, in which they are to be positioned when the wires are to be cut off and unwound, and a resting position, in which they are to be positioned out of reach of the bale when it is turned.
Moreover, conveyor belts may be arranged to transport the bale into and out of the working location (W), respectively.
Further, the device may comprise two cutting units and two winding units that are positioned pairwise opposite each other, on one side each of the working location.
The invention also relates to the cutting unit as described above.
Preferably, the cutters of the cutting unit are rotatable about an axis, which is intended to extend perpendicularly with respect to the wire that is to be cut off.
Further, the cutting edges of the cutters extend axially along the axis in the continuation of the cutting tool to cut off objects that are located in the continuation of the cutting tool along the axis.
Preferably, the cutting unit has a flat front portion, which is arranged to face a working location at which the bale is to be positioned when its wires are cut off and removed from it.
The flat front portion may comprise a recess through which the cutting tool is arranged to be carried forth and back between a retracted position and a working position, whereby in the retracted position it is positioned behind the front portion, and whereby in the working position it protrudes through the front portion in order to carry out the cutting.
Further, a sensor may be arranged to localise the wire on the bale, whereby a driving device is also arranged to move the cutting unit along the working location, such that the cutting tool may be positioned in front of the wire to be cut off.
As a result of the above disclosed device and cutting unit, an efficient and reliable cutting of bale wires is achieved, which reduces the wastage of pulp in connection with cutting of the wires.
An additional advantage of the invention is that the driving of the different tools for winding and for cutting may be the same. The only thing that has to differ between the two devices is the head of the tool, where the cutting tool shall be provided with two opposite surfaces, of which at least one is sharp, while the winding tool is instead provided with a gripping appliance for picking up the wires.